Ultrafiltration assembly having centrifugal pump and eductor

ABSTRACT

A portable ultrafiltration device for treating a mixed liquids stream is disclosed having a centrifugal pump, membrane filter cartridges, an eductor including a primary inlet, a suction inlet and an outlet all controlled by a control mechanism. The device includes a mechanism to transport treated liquid to a reservoir and a mechanism to recycle a portion of treated liquid form the filter cartridges to the primary liquid of the eductor while feed liquid is introduced through the eductor suction inlet.

This application is a Continuation-In-Part of U.S. patent applicationSer. No. 08/061,076 filed May 14, 1993, now U.S. Pat. No. 5,395,514.

FIELD OF THE INVENTION

This invention relates to an improved assembly for the separation ofwater from mixtures with larger molecule liquids such as oils,particularly to a new eductor pump, portable ultra-filtration system andassembly and novel fluid pick-up assembly which enhances theultrafiltration process.

BACKGROUND OF THE INVENTION

It is not unusual to find mixtures of water with larger moleculeliquids. For example, bilge water typically comprises a mixture of oilwith water, as does typical liquid waste collections from automotiverepair and wash facilities, machine shops, metal stamping plants, andgenerally any repair and/or industrial facility where fluids such asoils, coolants, antifreeze or the like may be commingled in use orcollection with water.

There has been an increasing need for means to separate such largermolecule liquids and water mixtures so that clean water can be returnedto the environment and larger molecule fluids can be recovered andrecycled for further use. Federal, state and local governments havepromulgated and instituted new laws concerning the handling and disposalof such mixtures, particularly oil/water mixtures, such that it hasbecome increasingly economically desirable to separate out as much wateras possible from such mixtures, conveniently at the site of commingling,to reduce the volume of liquid to be otherwise collected for recycle ordisposal off site. Thus, there is an increasing need for a convenient,portable device which will effectively and economically separate waterfrom larger molecule liquids, particularly petroleum oils and coolants,to provide a reduced volume for collection, recycle and disposal atremote sites.

One device which has been proposed and is generally commerciallyavailable for the separation of such mixtures is the ultrafiltrationdevice. In a typical ultrafiltration device a fluid containing mixture,such as oils with water is directed, under typically low pressure, to anultra-filtration membrane. The ultra-filtration membrane comprisesmicroscopic hydrophilic pores which will allow water to pass through themembrane but resist the passage of the oil molecules. Such selectiveactivity is a function of the membrane, achieved through a combinationof membrane characteristics including pore size, liquid contact angleand liquid surface tension. The membrane is typically arranged in across flow configuration wherein a feed mixture from a water/oil mixtureflows across the ultrafiltration membrane in such manner that the oilcomponent of the mixture does not flow through the membrane but aportion of the water in the mixture will permeate the membrane at a lowbut acceptable pass-through rate. Thus, water flowing through themembrane comprises essentially no oil and can be recovered or wasted, inmany instances without further treatment, while the treated mixturewhich does not permeate the membrane has an increased oil to waterratio. Typically the treated oil mixture, having an increased oil towater ratio, is returned to the feed mixture and is continually recycledin mixture with the feed mixture until the amount of water in thewater/oil feed mixture has been significantly reduced.

Ultrafiltration devices of the type above described have typically beencumbersome units that require costly tending by the operator during theseparation process to avoid harm to the membranes. Generally such priorart devices require extensive and complex disassembly procedures forroutine cleaning and/or maintenance and as a result such units have notenjoyed a level of commercial success that might otherwise be expected.Such low pressure devices of the prior art also typically require about24 hours or more to separate enough water from a 190 Liter containercontaining a typical 90:10 (water:oil) mixture to achieve asignificantly concentrated typical 50:50 (water:oil) mixture whileattaining an essentially oil free water waste containing less than about50 ppm of oil.

Various improved ultrafiltration devices are disclosed in U.S. Pat. Nos.4,994,184, 5,069,780 and 5,075,002 which utilize a unique combination ofcomponents that provide increased efficiency in a low pressureultrafiltration process and significantly reduce the time required toobtain a satisfactory water:oil mixture and provide an essentially oilfree waste. Though such improved devices have enjoyed commercialsuccess, there is a continuing desire to further reduce processing time,save energy costs associated with the process and resolve various of theproblems associated with typical pre-filter requirements.

It is an object of the instant invention to provide a portableultrafiltration device, capable of separating water from larger moleculeliquids such as oils, coolants, antifreeze and the like, to attain waterwaste containing less than about 50 ppm of the larger moleculecontaminant that is simplified in operation and disassembly, provideshigher pressures along the ultrafiltration membrane to assist indecreasing processing time and is internally protected from harm tocostly membranes.

It is a further object of the invention to provide an improved feedmixture pick-up tube comprising a self-cleaning pre-filter means.

Additional objects and advantages of the invention will be set forth inpart in the description which follows, and in part may be obvious fromthe description of the invention that follows, or may be learned bypractice of the invention. The objects and advantages of the inventionmay be realized and attained by means of the instrumentalities andcombinations particularly pointed out in the appended claims.

SUMMARY OF THE INVENTION

The present invention features an ultrafiltration device generallycomprising a centrifugal pump, membrane filter membrane elements, aneductor means comprising feed input means at the suction side, returnmeans, waste outlet means and means for controlling the device.Typically, a portable embodiment of the device is mounted to a wheeledsupport frame. Typically also the device comprises temperature andpressure sensing means, placed to detect temperature and pressurevariations of a feed mixture being processed by the ultrafiltrationdevice, and means cooperating with said temperature and pressure meansto interdict the operation of the device to prevent damage to thecomponents.

Provision is also made for an improved feed mixture pick-up assemblycomprising a means for directing reverse fluid flow through a screeningmeans which functions as a pre-filter means for feed mixture pick-upfrom a particulate laden feed mixture.

BRIEF DESCRIPTION OF THE DRAWINGS

The nature and mode of operation of the present invention will now bemore fully described in the following detailed description taken withthe accompanying drawings wherein:

FIG. 1 is a front perspective view of a typical portable ultrafiltrationunit of the invention.

FIG. 2 is a rear plan view of the unit of FIG. 1.

FIG. 3 is a front sectional view taken along about line 3--3 of theultrafiltration unit of FIG. 1, showing major components of a typicalassembly of the interior of the unit, set up in a typical arrangementfor ultrafiltration of an oil/water mixture such as a coolant/watermixture contained in a holding container.

FIG. 4 is a flow diagram showing the fluid flow through a typicalultrafiltration assembly of the invention.

FIG. 5 is a partial sectional plan view of a holding containercomprising an embodiment of a fluid pick-up assembly of the invention.

FIG. 6 is a sectional view of the fluid pick-up assembly of FIG. 5,taken along about line 6--6.

FIG. 7 is an enlarged fragmentary sectional view of a cartridge assemblyof FIG. 3 containing a ultrafiltration membrane element.

FIG. 8 is a top sectional view taken along about line 8--8 of FIG. 7.

FIG. 9 is an enlarged fragmentary sectional view of a cartridge assemblyof FIG. 3 taken in the area designated FIG. 9.

FIG. 10 is a sectional view of the fluid pick-up assembly of FIG. 6,taken along about line 10--10.

FIG. 11 is a sectional view of the fluid pick-up assembly of FIG. 6,taken along about line 11--11.

FIG. 12 is a fragmentary sectional view of the lower end of a furtherembodiment of a fluid pick-up assembly of the invention.

FIG. 13 is a sectional view of the fluid pick-up assembly of FIG. 12,taken along about line 13--13.

FIG. 14 is a sectional view of the fluid pick-up assembly of FIG. 12,taken along about line 14--14.

FIG. 15 is a sectional view of the fluid pick-up assembly of FIG. 12,taken along about line 15--15.

FIG. 16 is a fragmentary view of the lower end of a further embodimentof a fluid pick-up assembly of the invention.

FIG. 17 is a sectional view of the fluid pick-up assembly of FIG. 16,taken along about line 17--17.

FIG. 18 is a sectional view of the fluid pick-up assembly of FIG. 16,taken along about line 18--18 of FIG. 17.

FIG. 19 is a sectional view of the fluid pick-up assembly of FIG. 16,taken along about line 19--19 of FIG. 17.

DESCRIPTION OF THE PREFERRED EMBODIMENT

It will be understood at the outset that the ultrafiltration device ofthe present invention possesses utility in diverse applications ofultrafiltration wherein water is to be separated from larger moleculeliquids. However, in order to facilitate description of the presentinvention, specific reference will now be made to its use in associationwith removing water from a water/lubricating oil mixture contained in astandard 190 Liter (55 gallon) or similar reservoir.

FIGS. 1, 2 and 3 illustrate a portable ultrafiltration assembly of theinvention as generally including upper frame shroud 10, lower frameshroud 20 and base frame assembly 30, interconnecting to form thegeneral supporting frame of the assembly. Upper frame shroud 10generally acts in support of the instrumentation and controls of theunit and comprises handle 1 and an instrument control panel comprisingtemperature indicator 3, pressure indicator 2, indicator lights 4a, 4band 4c, apparatus on/off switch 5, start/restart switch 5a, and fuse 6.Lower frame shroud 20 is typically louvered 11 to provide means tocirculate cooling ambient air through the unit. Centrifugal pump 22 maycomprise heat exchange fins 57 for passive exchange of heat to the airfrom the pump, and fan 58 is provided for forced circulation of ambientair through louvers 11 and about the interior of the apparatus. Incircumstances where the ultrafiltration process, particularly thepumping process, generates significantly more heat than can be easilydissipated by fins 57 and/or fan 58, it is contemplated as within theinvention to include heat exchange means elsewhere in the processstream. For example, a passive radiation heat exchange means may beincorporated in the feed mixture input and may be interior or exteriorto the assembly for dissipation of heat to ambient air, or the systemmay contain refrigeration capability.

In the portable embodiment, base frame assembly 30 supports axle 29 andcomprises axle mounts 32, wheels 7 and support leg 46. Centrifugal pump22 is driven by motor means 28, is mounted to base frame assembly 30 bymount 31, and contains temperature sensing means 35.

FIG. 2 generally illustrates the rear of the assembly wherein reservoirfeed mixture input line 15 and waste water line 18 emerge from rearaccess panel 9.

Reservoir feed mixture input line 15 connects to suction side 12 ofeductor 34 to provide feed mixture input to the ultrafiltrationassembly. Feed mixture input connecting line 16 carries the feed mixturefrom eductor 34 to centrifugal pump 22 of the apparatus. Treated feedmixture return line 17 and waste water line 18 are shown in section anddepict fluid lines returning to feed mixture reservoir 19 and wastewater receptacle 21 respectively.

FIG. 3 illustrates the general arrangement of components contained inthe interior of the ultrafiltration assembly of FIG. 1 together with atypical feed mixture reservoir and waste water receptacle arrangement.Therein, screened feed mixture flows from pick-up assembly 40 throughfeed mixture input line 15 into suction side 12 of eductor 34, througheductor outlet 13 to feed mixture line 16 where it is directed tocentrifugal pump 22. In the illustrated embodiment centrifugal pump 22pumps the feed mixture through input line 23 to cartridge 24 whichcontains a first ultrafiltration membrane element. Cross flow filteredfeed mixture flowing from cartridge 24 is passed through connecting line25 and through a second ultrafiltration membrane element contained incartridge 26. It should be understood that it is contemplated to useother arrangements of membranes or the like means suitable forultrafiltration and the present invention is not meant to be limited toultrafiltration cartridges and/or membranes.

The flow arrangement of feed mixture illustrated in the drawings toultrafiltration cartridges 24 and 26 is a preferred serial flow pathwherein the feed mixture comprises a water and petroleum oil mixture andthe two ultrafiltration membranes are contained in single chambercartridges. It should be understood that it is contemplated as withinthe scope of the invention that the arrangement comprise a singleultrafiltration membrane which may or may not be contained in acartridge environment and that the flow path alternately be a parallelflow path or a combination of serial and/or parallel flow paths whereinthe assembly comprises three or more ultrafiltration membranes, whichmay or may not be in cartridges and/or chambered units.

In the drawings, the treated mixture passes from the ultrafiltrationmembrane containing cartridges through connecting line 33 to diverter 8wherein a portion of the treated mixture is directed through a reducedsized orifice to treated feed mixture return line 17 and then toreservoir 19. Waste water removed during ultrafiltration is collectedfrom cartridges 24 and 26, passes through waste water manifold 27 and ispassed through waste water line 18 to waste water receptacle 21. Itshould be understood that typically the waste water can be directlysewered to waste, or in many instances can be reused.

Referring now to FIG. 4, therein is schematically illustrated apreferred arrangement of components for fluid flow through anultrafiltration unit of the invention, including placement of optionaltemperature and pressure sensors. Therein, centrifugal pump 22 moves awater/oil feed mixture from feed mixture input line 16 through line 23to membrane cartridge 24.

Temperature sensing means monitor the temperature of the feed mixture atone or more points in the fluid flow to determine that fluid contactingthe ultrafiltration membranes is not heated to a temperature whereindamage to the membrane can result. In the flow schematic of FIG. 4,temperature sensor 35a is placed in a fluid flow between a pre-filterand the cartridge and temperature sensor 35 is placed within thecentrifugal pump. Typically, in situations where the pump is directlyinterconnected to an electric motor drive as a unit structure, anappropriate thermal switch 35b, which acts to interrupt power to themotor in response to motor heat, can function as an indicator of feedmixture temperature and automatic cut-off of feed mixture flow to themembranes. Generally, a single temperature sensor can be placed toprovide adequate monitoring of temperature variations.

Temperature sensors can be arranged in conjunction with a temperatureindicator for visual observation and manual control of the unit,however, they are preferably arranged together with an automatic limitswitching means for interdicting the flow of fluid through anultrafiltration cartridge, generally by interrupting power to thecirculating pump, upon sensing of a temperature outside the limitingrange. In the preferred embodiment of the drawings, a temperature sensor35 is located at the pump which is coupled with visual temperatureindicator 3 provided on the control panel of the upper frame shroud 10.In a further preferred embodiment a second temperature sensor 35a islocated at ultrafiltration cartridge 24 and also comprises an automaticlimit switching means which interrupts power to circulating pump 22 uponsensing a temperature outside a preset range. In the illustratedinvention, indicator light 4c at the control panel of the upper frameshroud turns on when the circulating pump has been interdicted byexceeding temperature limits. It should be understood that contemplatedas within the scope of the invention is placement of such temperaturesensing means and/or automatic limit switching means elsewhere in theultrafiltration unit, as for example temperature sensor 35b can belocated in the electric motor of the pump and will interrupt operationof the motor upon exceeding a preset temperature, or, placingtemperature sensing means at a point in the fluid stream at or beyondthe ultrafiltration cartridges and adjusting interdiction to occur atadjusted temperatures. Though it has been found convenient in theembodiment of the invention illustrated in the figures to manuallyrestart the system, after interdiction, by manual restart switch 5a, itis also contemplated as within the invention to include automaticswitching means that reconnects current to the circulating pump uponsensing a return of the temperature of the feed mixture to the desiredtemperature range or after a preset time interval.

In general, temperature interdiction means are included when theapparatus may be used in environments wherein components of theapparatus, principally the ultrafiltration means and/or pumping means,may be subjected to temperature variations beyond their physicallimitations. Generally interdiction means are established to limitationswithin the physical limitations of the apparatus. In one embodiment anultrafiltration assembly of the invention comprises one or more spiralwound ultrafiltration membranes in spaced configuration so as to formseparate spiral feed mixture and filtered effluent chambers. Suchconfiguration generally comprises separators, arranged to maintain thespaced configuration, which are generally held in place by glues,adhesives or the like. Generally it has been found that with suchmembranes, feed mixtures which are at temperatures less than about 0°Centigrade create processing inefficiencies, apparently because ofsignificantly increased viscosity of the feed mixture. Feed mixturetemperatures exceeding about 150 degrees Centigrade have also been foundto create processing inefficiencies, through the weakening of thermallysensitive adhesives which maintain separators in place and/or byweakening the structural integrity of the ultrafiltration membraneswhich can significantly reduce the efficiency of the ultrafiltrationprocess. In other environments, temperature interdiction occurs inresponse to overheating of the circulation pump or the like.

Though both low and high temperature limit switching is contemplated asembodiments within the invention, generally low temperature switching isobviated by simple observation of the operator and is not typically anecessary component of the invention. Typically temperature sensorswhich are suitable for use in the invention interrupt the power to acirculating pump and are those having an upper temperature limitationabove about 140 degrees Centigrade.

Pressure sensing means 36 are also provided for in a preferredembodiment and are generally placed to monitor the pressure of the feedmixture at one or more points in the fluid flow so that fluid contactingan ultrafiltration means, particularly a membrane, is within anefficient ultrafiltration pressure range and wherein damage to themembrane, circulating pump and/or other components can be avoided. Inthe illustrated embodiment, a pressure sensor is preferably placed inthe fluid flow at a point from the circulating pump to inlet 14 ofeductor 34. A most preferred placement is between the circulating pumpand a final ultrafiltration membrane. Pressure sensors can be arrangedin conjunction with a pressure indicator for visual observation andmanual control of the unit, however, they are preferably arrangedtogether with an automatic limit switching means to interdict the flowof fluid through an Ultrafiltration membrane. Generally interdiction isachieved by interrupting the power operating the circulating pump, uponsensing of a pressure outside the limiting range. Most preferably thepressure sensing means comprises a high and/or low pressure sensingswitch that automatically turns off the circulating pump upon exceedingpreset pressure limits. The device control panel will indicateinterruption of the circulating pump at indicator light 4a so that theoperator is aware of the status of control. In the preferred embodimentof the drawings, cartridges 24 and 26 can comprise a pressure sensor 36on the feed mixture side of the membranes. Pressure sensor 36a providesinput to pressure indicator 2 for visual observation of pressure, whilepressure sensor 36 comprises an automatic limit switching means whichinterrupts power to the circulating pump 22 upon sensing a pressureoutside a preset range. In the illustrated invention, indicator light 4aat the control panel of the upper frame shroud turns on when thecirculating pump has been interdicted by exceeding pressure limits.

Though it has been found convenient in the embodiment of the inventionillustrated in the figures to manually restart the system, afterinterdiction, by manual restart switch 5a, it is also contemplated aswithin the invention to include automatic switching means thatreconnects current to the circulating pump and can restart thecirculating pump when the desired pressure ranges are again attained.

In general, pressure interdiction limits depend upon the physical limitsof the components of the apparatus and most particularly upon thelimitations of the ultrafiltration membrane as well as the fittings andmaterials of construction of the assembly. Typically, spiral woundmembranes can handle pressures well in excess of 200 psi. Generally, itis more time efficient to run a spiral wound membrane system at higherpressures with appropriate matching of flow rates.

Returning now to FIG. 4, feed mixture is pumped out of the centrifugalpump, under pressure, and flows by means of input line 23 to the firstultrafiltration cartridge 24, wherein it contacts, under pressure incross-flow, membrane A. Water contained in the mixture crosses theultrafiltration membrane for wasting through generally non-pressurizedor suction enhanced, waste water line 18. The feed mixture, still underpressure from the action of the circulating pump, exits the firstultrafiltration cartridge 24 through connecting line 25 and istransported to ultrafiltration cartridge 26. Still under pressure, thefeed mixture contacts ultrafiltration membrane B wherein water containedin the mixture crosses the membrane for wasting through waste water line18. The treated feed mixture flows through line 33 to diverter means 8.Diverter means 8 merely comprises an outlet through which a portion ofthe treated feed mixture can flow through line 17 back to the feedmixture reservoir 19. The non-diverted treated feed mixture flows, undera maintained pressure, through line 36 to inlet 14 of eductor 34.

The diversion of the treated feed mixture through line 17 is restrictedto assist in maintaining fluid pressure in the system. Generally, anysuitable means to accomplish the restriction can be used, such as arestricting orifice, restricting line or the like. Preferably, therestriction comprises a restricting line.

Eductor 34, generally also known as an ejector, syphon, exhauster and/orjet pump, comprises a venturi wherein an activating fluid flowing frominlet 14 to outlet 13 creates a suction through suction inlet 12. Theventuri, being a restrictive passage, also restricts the fluid flowthrough line 36 thus assisting in maintaining fluid pressure in thesystem. Thus, as treated feed mixture flows under pressure througheductor 34, a suction is created at suction inlet 12 which causesadditional feed mixture to flow from reservoir 19 through feed mixtureinput line 15, through suction inlet 12, which combines with the treatedfeed mixture that is passing through the venturi of eductor 34 fromeductor input line 41, to constitute the feed mixture that flows throughfeed mixture line 16 into circulating pump 22.

The eductor provides multiple roles in the system of the invention. Itacts as a pressure control orifice to maintain pressure within thesystem from the pump to the eductor and thus maintain a feed mixturestream pressure against the ultrafiltration membrane and maintain aminimal change in fluid pressure along the length of the ultrafiltrationmembrane. It also acts as a suction pump to pump feed mixture from thereservoir to the input side of the circulation pump and as a suctionpressure boost to the centrifugal pump receiving the feed mixture.

The operating efficiency of a given ultrafiltration membrane unit istypically dependent upon an optimum preferred rate of fluid flow alongthe membrane and an optimum pressure of such fluid against the membrane.Generally, the attaining of optimum operating efficiency of anultrafiltration membrane has been further limited by the inability tomatch optimum flow rates with optimum pressure in conveniently availablecommercial centrifugal pumps.

In U.S. Pat. No. 5,075,002 an ultrafiltration system comprising acartridge type spiral wound membrane, was disclosed wherein the flow offluid along the membrane was controlled by incorporating a flowrestricting orifice in the system beyond the membrane. The steady statepressure against the membrane, for any flow restricting orifice, was afunction of the pressure developed by the centrifugal pump driving thesystem and for a given flow rate was limited by the size of the pump,the motor driving the pump and the design of the impeller. Thus in suchsystem utilizing conventionally available centrifugal pump and impellerdesign, an increase in steady state pressure at a desirable flow raterequires bigger pumps and/or motors which means an inconvenient increasein motor size and/or increase in power consumption.

Interestingly, I have found that steady state pressure against themembrane can be increased in such system without resorting to uniquedesigned centrifugal pumps and/or increased sized pumps and/or toincreased size motors and/or increasing power consumption. I have foundthat by providing an eductor in a partial recycle loop of a centrifugalpump driven ultrafiltration system, the steady state pressure of thesystem for a given flow rate can be increased without correspondingincrease in the motor size and/or power consumption of the centrifugalpump.

Though I do not wish to be bound by the following, what appears to behappening is that the eductor provides pressurized fluid at thecentrifugal pump intake, thus boosting the suction pressure at theintake. The boost in suction pressure reduces the amount of kineticenergy that would otherwise be used by the centrifugal pump to drawfluid from the reservoir. Thus, at least a portion of the kinetic energyusually expended by the centrifugal pump to suck fluid into the pump isexpended by the pump in increasing the pressure at the outlet side ofthe pump and the kinetic energy of the increased pressure from theoutlet of the pump is used by the eductor to boost the suction pressureon the intake side of the pump. When the pump reaches a desired steadystate flow rate, as controlled by the restriction of diverted returnmixture and the restriction of the orifice of the eductor venturi, theamount of energy needed to drive the pump is reduced and there is acorresponding decrease in motor power consumption.

The eductor appears to be participating in the system as a conservatorof energy. When the system merely comprises a restrictive orifice, thekinetic energy which has been imparted to the fluid by the centrifugalpump dissipates to the reservoir and/or atmosphere on exiting therestriction. When the restrictive orifice comprises an eductor, the exitof the restrictive orifice comprises a suction tap which uses thekinetic energy from the fluid to pump additional fluid to thecirculating pump. Thus, the kinetic energy of the fluid entering thecirculating pump becomes in part additive to the kinetic energydeveloped by the pump, which in turn is imparted to the fluid flowingtherefrom in the form of increased pressure.

The selection of the restriction of the diverted return feed mixture andthe size of the orifice of the eductor is dependent upon the operatingcharacteristics of the pump and the characteristics of the fluidtransmission system from the circulating pump to the orifice. Generally,it is preferred that the characteristics of the pump and the system besuch as to provide the desired fluid flow rate and produce an outputhead from a non-pressurized intake which is sufficient, when restrictedby the orifice of the eductor and the diverted restricted feed mixturereturn, to provide less than 100% of the desired pressure at theultrafiltration membrane. I have found that with careful selection andmatching of the eductor orifice and the restricted feed mixture returnthe pressure of the system, when provided with suction feed pressureboosting from the eductor, can be raised from 10 to 50% over that of anon-suction feed boosted system.

I have found that when using commercially available spiral woundmembranes it is preferable that the pressure be maintained at from about50 to about 195 lbs/in² pressure and most preferable when the pressureis from about 70 to about 150 lbs/in². Operating the assembly under suchconditions has acted to reduce the water content of a 90:1 water oilmixture contained in a 190 Liter (55 gallon) container to a 50:50mixture in less than 4 hours in experimental tests.

FIGS. 7 and 8 illustrate a typical ultrafiltration membrane cartridgecontaining a membrane element operable with the invention. Therein isshown a typical first ultrafiltration cartridge 24 wherein feed mixtureis transported through feed mixture input line 23 to cartridge feedmixture inlet 39. Therein it flows from collection chamber 48 throughpassages 51 between sandwiched, spiral wound, ultrafiltration membranes52, the sandwiched membranes being held apart by separators 53. Feedmixture flowing from between the sandwiched membranes is collected atcartridge lower area 54 and flows through spacer 55, through feedmixture outlet 38 into connecting line 25. Water diffusing throughultrafiltration membranes 52 collects within the sandwiched membranes,flows through openings 49 to central chamber 50 and out cartridge wastewater outlet 37 to waste manifold 27.

FIG. 9, illustrates the configuration of the lower area of cartridge 26in FIG. 3, wherein outlet 56 inputs treated feed mixture to diverter 8through line 33.

Ultrafiltration materials useful in the assemblies of the invention arewell known in the art and generally include any materials which resistthe passage of materials smaller than about 1 micron in size andpreferably down to about 1 nano. Generally, such materials can be of anysuitable shape or configuration but preferably the materials are in theform of a membrane which may be pliable, rigid and/or deposited orotherwise appended to a pliable and/or rigid structure. In a preferredembodiment, the material is configured as spiral wound, flat sheet,hollow fiber, tubular or combinations thereof.

Flat sheet materials are generally arranged as membranes in amultilayered sandwiched configuration and as with spiral wound aregenerally interspaced with structure such as spacers and the like whichassist in maintaining the spaced integrity of feed mixture and effluentchambers.

Hollow fiber and tubular materials generally comprise deposited or thelike membranes and are generally arranged in self-supportingconfigurations. In one embodiment, a hollow(s) of the fiber and/or tubereceives the influent feed, the material comprising the fiber and/ortube surrounds the influent feed and the filtered fluid escapes from theexterior wall. In such embodiment, the integrity of the materialcomprising the membrane is generally sufficient to resist the pressureof the feed mixture and maintain the structural integrity of the fiberand/or tube.

In another embodiment, the influent feed surrounds the exterior wall ofthe fiber and/or tube and filtered fluid escapes through the interiorwall to a hollow of the fiber and/or tube. Such embodiment, generallyprovides an advantage to cleaning and/or backwashing the membrane.

Of the great number and variety of ultrafiltration materialscommercially available and useful in the useful under varyingultrafiltration conditions in the apparatus of the invention, membraneswhich are particularly useful include the polymer blended membranes,PVDF membranes, teflon membranes, polysulfone membranes and the coatedceramic membranes.

One particularly preferred arrangement comprises a spiral woundconfigured, cartridge type membrane which resist flow therethrough ofmolecules having a molecular weight greater than water. Typically suchmembranes have an operating pH range of about 2-11, an operatingpressure range of from about 40-400 psi and an operating temperaturerange up to about 100° Centigrade. Polysulfone and PVDF base membraneshave been found to be particularly suitable for the ultrafiltrationassembly of the invention, particularly membrane cartridges containingelements comprising a gross contact area of from about 1.5 to about 9Meters² and most preferably about 2.75 Meters.

Though the various feed mixture pick-up assemblies of the prior art aresuitable for use with the ultrafiltration device of the invention,assemblies that comprise a means for filtering and/or otherwisescreening particulate matter from the feed mixture and one whichcomprises a self-cleaning filtering and/or screening means is mostdesirable.

I have found that in processes wherein a stream of fluid is being pumpedinto a fluid reservoir coincidentally with a fluid stream being pumpedout, such as the process of the ultra-filtration device of theinvention, that a novel combination of components allows the fluid beingpumped into the reservoir to be utilized to enable self-cleaning of aparticulate screening means. By particulate screening means is meant thevarious mesh screens, porous membranes, films or the like materialswhich are commonly adapted to comprise passageways which are sized toallow the flow of fluids therethrough but which form a barrier to theflow of particulate matter that may exceed such size.

By adopting the feed mixture pick-up assembly to direct fluid flowinginto the reservoir to cause a recurrent reverse flow of fluid throughminor portions of the particulate screening means, coincidentally withthe forward pumping of fluid from the reservoir through other portionsof the screening means, the screening means can be regularly cleaned toresist clogging without interruption of the process of pumping fluidfrom the reservoir.

FIGS. 5, 6, 10 and 11 illustrate an embodiment of a self cleaningpick-up assembly which is particularly suitable for use with theultrafiltration assembly of the invention. FIG. 5 shows a pick-upassembly 40 engaging reservoir 60. The pick-up assembly is illustratedas comprising a housing designated as hollow support tube 61 comprisingdrum fitting 62 for engaging an access aperture of reservoir 60, whichis illustrated as comprising a 55 gallon drum. Hollow support tube 61comprises upper seal 63, which engages a feed mixture return passagewayillustrated as central return tube 64 and a fluid outlet passageway 65which is illustrated as concentric to return tube 64 and furthercomprises outlet tube 59 in fluid communication with passageway 65.Spacer 66 engages feed mixture return tube 64 and comprises holes 67through which fluid can flow from the fluid pick-up subassembly tooutlet passageway 65.

In use with the ultrafiltration device of the invention, the feedmixture return tube is in fluid communication with feed mixture returnline 17 of the device and outlet tube 59 is in fluid communication withfeed mixture input line 15.

The fluid pick-up subassembly generally comprises bearing housing 68which engages an end of feed mixture return tube 64, bearing 69 which ismounted in said housing, connecting tube 71, angle tube 72 and nozzle73. Connecting tube 71 is mounted to bearing 69 such that it isrotatable around about the longitudinal axis of fluid flow from feedmixture return tube 64 though housing 68 and bearing 69. Connecting tube71 is connected to angle tube 72 which in turn is connected to nozzle73.

Screen 74 surrounds angle tube 72 and is coupled to support tube 61 bycoupling means 75. Angle tube 72 is configured to comprise an angletherein such as to direct the flow of fluid at an angle, preferableabout a 90° angle, to the longitudinal axis of connecting tube 71.Nozzle 73 comprises a restriction at its outlet and is configured todirect fluid flow at a tangent to the direction of the longitudinal axisof connecting tube 71 and against screen 74.

In such embodiment, the restriction at the nozzle maintains a pressurein the fluid flowing through feed mixture return assembly. The change indirection of fluid flowing from along about the longitudinal axis of theassembly through an outlet in a direction tangential to suchlongitudinal flow causes rotation of the nozzle, angle tube andconnecting tube which is facilitated by the bearing. Fluid flowing fromthe rotating nozzle hits against and flows through the screen as thenozzle rotates thus dislodging particles which may be laying against andwithin the holes of the screen.

In a typical operating arrangement outlet tube 59 of the fluid pick-upassembly has a suction imposed thereon from a pump means. In combinationwith the ultrafiltration device of the invention, outlet tube 59 wouldbe connected to the suction side of the eductor through feed mixtureinput line 15. Fluid from the reservoir would be drawn through screen74, through holes 67 of spacer 66 into outlet passageway 65, thoughoutlet tube 59 and through input line 15 to suction side 12 of eductor34. Partially diverted fluid from the diverter of the ultrafiltrationdevice would pass through line 17 to feed mixture return tube 64 to thefluid pick-up subassembly wherein it would pass through screen 74 and tothe reservoir.

It should be understood that various embodiments of the fluid pick-upsubassembly are contemplated as falling within the broad description ofthe invention. For example it is contemplated that the subassemblycomprise a sphere such as a ball or the like, which is confined within apassageway between an outlet of fluid being returned to the reservoirand a means for screening fluid being pumped from the reservoir. Theaction of the fluid exiting the opening of the outlet and hittingagainst the sphere causes it to rotate and/or move about the confinedpassageway such that the sphere presses against the screen causing fluidto be squeezed though the holes therein and causing particulate matterwhich may be clogging the screen back into the reservoir.

Similarly, by further example, the means for directing fluid flowingfrom the outlet of fluid being returned to the reservoir may comprise aslotted rounded member, which rotates about an axis with the passage offluid through the slot and splashes fluid against the screen to effectreverse flushing of the screen.

FIGS. 12-15 and 16-19 illustrate embodiments of the aforesaidexemplified pick-up subassemblies specifying only the fluid pick-up endsof the assemblies, which coact with the fluid in the reservoir. In anultrafiltration application such as that of the invention, passageways85 and 85a comprise fluid return passageways which engage return line 17of the illustrated ultrafiltration device and passageways 84 and 84acomprise fluid outlet passageways that engage feed mixture suction inputline 15.

In the embodiment illustrated in FIGS. 12-15, the housing is illustratedas comprising a hollow support tube 61a having a central tube 83defining fluid outlet passageway 84 which cooperates with spacer 86,comprising passageways 87, to form discrete concentric fluid returnpassageway 85.

Outlet passageway 84 engages the feed mixture return subassembly whichcomprises axle support frame 88, axle 89 and slotted rotatable cylinder90 which has an angular external slot 92 and an internal hollowpassageway 91 that comprises a central support frame 93 for rotatablymounting the cylinder to the axle. Cylindrical screen 94 is mounted inspaced concentric relationship to cylinder 90 and comprises a plate 95having a central hole for mounting the screen on axle 89. The screen ismounted in an arrangement such that pressurized fluid flowing from theultrafiltration device through return passageway 85 flows throughpassageways 87 of spacer 86, through open end 96 of cylindrical screen94 and engages slot 92 of rotatable cylinder 90.

Rotatable cylinder 90 is loosely mounted to axle 89 and arranged suchthat fluid flowing through the angular shape of slot 92 causes cylinder90 to rotate about axle 89, in a manner similar to fluid engaging bladesof a turbine to cause it to spin. Cylindrical screen 94 is cooperativelymounted with collar 82, spaced from rotatable cylinder 90, such thatrotation of cylinder 90 causes fluid flowing through slot 92 to splashagainst and through screen 94, carrying particulate material which maybe lying against and within the holes of screen 94 along with it intothe reservoir.

Feed mixture input line 15 of the ultrafiltration device is in fluidcommunication with central fluid outlet passageway 84 which is in fluidcommunication with internal hollow passageway 91 of cylinder 90. End 97of cylinder 90 is arranged in spaced relationship to plate 95 of screen94, by means of spacer 98, such that fluid can flow therebetween.

In the operation of the fluid pick-up assembly of this embodiment, afluid suction is imposed by pump means of the ultrafiltration apparatusthrough feed mixture input line 15 which is in screened fluidcommunication with the reservoir through the spaced relationship ofhollow passageway 91 with plate 95 of screen 94. Coincidentally, fluidpressure is imposed by pump means of the ultrafiltration apparatusthrough return line 17 which is in screened fluid communication with thereservoir through the spaced relationship of slot 92 with screen 94.Thus, fluid flows from the ultrafiltration device to the reservoirthrough those areas of screen 94 which are adjacent slot 92 at any pointof rotation of cylinder 90; and, fluid flows from the reservoir throughscreen 94 to the internal hollow passageway from those areas of screen94 which are not adjacent slot 92.

It has been found that the force of the fluid flowing through the screeninto the reservoir tends to create a turbulence in the reservoir atleast in the area of the fluid pick-up end of the fluid pick-upapparatus which tends to keep the screen from clogging with particulatematter and provide a continuing mixing of returning fluid with thereservoir fluid.

In the embodiment illustrated in FIGS. 16-19, the housing is illustratedas comprising a hollow support tube 61b having discrete central tube 83adefining fluid outlet passageway 84a which cooperates with spacer 86a,having passageways 87a, to form discrete concentric fluid returnpassageway 85a.

The feed mixture pick-up subassembly generally comprises threadedcoupler 99, slotted hollow guide 100, ball 101 and screen assembly 102.Screen assembly 102 comprises screen housing 103 having threads 106,rounded screen 104 and screen attachment ring 105. Coupler 99 isgenerally glued or otherwise engaged to hollow support tube 61b andcomprises threads 107 for cooperating engagement with threads 106 ofscreen housing 103. Rounded screen 104 is mounted to housing 103 incooperative engagement with attachment ring 105, generally by gluing orthe like. Hollow guide 100, comprises attachment end 108 and conicalguide section 109 comprising slots 110. Guide 100 is mounted to centraloutlet passageway 84a such that slots 110 are in fluid communicationtherewith and is arranged in spaced relationship to rounded screen 104such that ball 101 can freely travel in a path around conical guidesection 109 of hollow guide 100 within the confines of screen 104.

Passageways 87a of spacer 86a are angled such that path of pressurizedfluid diverted through line 17 from the ultrafiltration device throughreturn passageway 85a is diverted by angular passageways 87a of spacer86a to engage ball 101 and cause the ball to move in a path around guide100 pressed against screen 104. Fluid which is in the feed mixturepick-up subassembly between the ball and the screen, is squeezed by theforce of the ball being pressed against the screen and is forced throughscreen 104, carrying particulate material which may be lying against andwithin the holes of screen 104 along with it into the reservoir.

Feed mixture input line 15 of the ultrafiltration device is in fluidcommunication with central fluid outlet passageway 84a of the housingwhich is in fluid communication with hollow guide 100 and slots 110 ofthe feed mixture pick-up subassembly such that fluid suction pumping bythe ultrafiltration device, pumps fluid from the subassembly which isreplenished by flow of fluid through the screen from the reservoir.

In the operation of the fluid pick-up assembly of this embodiment, afluid suction is imposed by pump means of the ultrafiltration apparatusthrough feed mixture input line 15 which is in fluid communication,through passageway 84a, slots 110 and screen 104 with the reservoir.Coincidentally, fluid pressure is imposed by pump means of theultrafiltration apparatus through return line 17 which is in screenedfluid communication with the reservoir through passageway 85a, spacerpassageways 87a and screen 104. Thus, fluid flows from theultrafiltration device through those areas of screen 104 which areadjacent ball 101 at points of travel of the ball along its path to thereservoir; and, fluid flows from the reservoir through screen 104 to theoutlet passageway 85a from those areas of screen 104 which are notadjacent the ball.

It should be understood that various modifications of the illustratedassemblies are evident therefrom which can be seen as providingequivalent functions in the assembly, each of which are contemplated aswithin the scope of this invention.

I claim:
 1. A filtration assembly comprising:a centrifugal pump meanshaving an inlet and an outlet; eductor means, having a primary inlet, anoutlet and a suction inlet, said outlet of said eductor means being influid communication with said inlet of said centrifugal pump means andsaid suction inlet of said eductor means being in fluid communicationwith a reservoir comprising a mixture of liquids to be treated; meansfor filtering arranged to receive a stream of influent liquid feedcomprising a mixture of liquids of differing molecular size from saidoutlet of said centrifugal pump means, and enabled to treat said streamand separate a liquid of selected molecular size from said stream; meansfor transporting the treated stream from an outlet of said filteringmeans to said primary inlet of said eductor means; means fortransporting at least a portion of the treated stream from an outlet ofsaid filtering means to said reservoir; wherein said respective meansfor transporting together are cooperatively arranged to maintain asufficient liquid pressure for filtering said selected molecular sizeliquid from said liquid influent feed.
 2. The filtration assembly ofclaim 1 comprising sensor means including at least one of temperaturesensor means and pressure sensor means.
 3. The filtration assembly ofclaim 2 comprising means cooperating with a sensor means forinterdicting the operation of said centrifugal pump means.
 4. Theassembly of claim 3 comprising means cooperating with at least one ofsensor means for overriding interdiction of said pump means.
 5. Theassembly of claim 2 wherein said sensor means comprises a temperaturesensor, mounted to detect temperature variation at said pump means. 6.The assembly of claim 5 wherein said temperature sensor comprises athermal switch.
 7. The assembly of claim 5 comprising visual temperatureindicator means.
 8. The assembly of claim 2 wherein said sensor meanscomprises a pressure sensor, mounted to detect pressure variation ofsaid liquid feed.
 9. The assembly of claim 8 comprising visual pressureindicator means.
 10. The assembly of claim 2 wherein said sensor meansengages at least one visual display means.
 11. The filtration assemblyof claim 1 wherein said means for filtering comprises a water receivingzone which is separated from a liquid feed zone by a filter.
 12. Thefiltration assembly of claim 1 wherein said influent liquid feed ispre-filtered, prior to passage to said means for filtering, sufficientlyto filter particles from said liquids mixture.
 13. The assembly of claim12 wherein said influent liquid feed is prefiltered by pre-filter meanscomprising a screening means which filters out particles having a sizegreater than about 100 microns.
 14. The assembly of claim 1 wherein saidinfluent liquid feed comprises water and a liquid having a molecularweight greater than water.
 15. The assembly of claim 14 wherein saidinfluent liquid feed comprises oil and water.
 16. The assembly of claim15 wherein said influent liquid feed comprises petroleum oil and water.17. The assembly of claim 14 wherein said influent liquid feed comprisescoolant and water.
 18. The assembly of claim 1 comprising a supportframe.
 19. The assembly of claim 18 wherein said support frame ismounted to wheels.
 20. The assembly of claim 1 wherein said means forfiltering comprises a membrane filter assembly.
 21. The assembly ofclaim 20 wherein said means for filtering comprises two membrane filterassemblies.
 22. The assembly of claim 21 wherein said two membranefilter assemblies are arranged in serial flow communication.
 23. Theassembly of claim 1 wherein said means for filtering comprises a thinfilm membrane.
 24. The assembly of claim 1 wherein said means forfiltering is configured as a shaped selected from the group consistingof spiral wound, flat sheet, hollow fiber, tubular and combinationsthereof.
 25. The assembly of claim 24 wherein said means for filteringcomprises a membrane selected from the group consisting of polymerblended membrane, PVDF membrane, Teflon membrane, polysulfone membraneand coated ceramic membrane.
 26. The assembly of claim 25 wherein saidmeans for filtering comprises a spiral wound ultrafiltration membranecartridge having a gross contact area of from about 6 to about 18 ft².27. The assembly of claim 1 comprising means for dissipating heat fromsaid assembly.
 28. The assembly of claim 27 wherein said means fordissipating heat comprises heat exchange fins arranged on said pumpmeans.
 29. The assembly of claim 27 wherein said means for dissipatingheat comprises a fan arranged to direct air through said assembly. 30.The assembly of claim 1 wherein said means for transporting from saidmeans for filtering to said reservoir comprises means for restrictingflow of treated liquid from said means for filtering.
 31. The assemblyof claim 30 wherein said means for restricting liquid flow comprises anorifice means.
 32. The assembly of claim 31 wherein the opening of saidorifice means is variable.
 33. The assembly of claim 1 wherein saideductor means comprises an orifice means for restricting flow of liquidfrom said means for filtering.
 34. The assembly of claim 33 wherein theopening of said orifice means is variable.
 35. A portableultrafiltration assembly for separating water from an influent liquidstream containing greater than about 50 percent by weight watercomprising:a centrifugal pump having an inlet and an outlet; eductormeans, having a primary inlet, an outlet and a suction inlet, saidoutlet of said eductor means being in fluid communication with saidinlet of said centrifugal pump and said suction inlet of said eductormeans being in fluid communication with a reservoir comprising a mixtureof liquids to be treated; filtering means, comprising a hydrophilicultra-filtration membrane, arranged to selectively allow passage ofwater contained in said influent stream through said membrane; means fortransporting the treated stream from an outlet of said filtering meansto said primary inlet of said eductor means; means for transporting atleast a portion of the treated stream from an outlet of said filteringmeans to said reservoir; wherein said respective means for transportingtogether cooperatively enable passage of water through said membrane.